Process for the production of lubricating oil



June 25, 1935. B, BRAY Er A 2,006,096

PROCESS FOR THE PRODUCTION OF LUBRICATING OIL Filed Oct. 2, 1933J'ii'fraci Aspiak' IN VENTORS ATTORNEY.

V Patented June 25, 1935 UNITED STATES PATENT OFFICE PROCESS FOR THEPRODUCTION OF LUBRICATING OIL Ulric B. Bray, Palos Verdes Estates, andClaude E. Swift, Glendale, Calif., assignors to Union 1 Oil Company ofCalifornia, Los Angeles, Calif.,

a corporation of California Application October 2, 1933, Serial No.691,829 13 Claims. (Cl. 196-67) 5 filed August 4, 1931.

One of the distinctive characteristics of a lubri eating oil is itsviscosity. For many purposes lubricants are preferred which exhibit aminimum variation in viscosity with variation in temeprature, i. e. havelow viscosity temperature susceptibilities. It is generally known thatthe viscosity of lubricating oil produced from Western crude oils, suchas California naphthene base crudes which are crudes containing asphalt,varies more with change in temperature than lubricating oils producedfrom Eastern crude oils or paraflin base crudes. This means that if twosuch oils have an identical viscosity at 100 F., the Western oil willhave a much lower viscosity at the higher temperature of 210 F. than theparaflln base oil. This change in viscosity with temperature issometimes called the temperature viscosity sus prise distillates, thatis, fractions which have beenv vaporized from crude oil and condensed.Lubricating oils produced from paraflin base oils which containsubstantially no asphalt are generally produced by first distillinglight oil fractions including gasoline, kerosene and gas oil and alsotaking overhead light lubricating oils, called neutrals having aviscosity in the neighborhood of 100 to 200 seconds Saybolt universal at100 F., leaving an undistilled residue termed bright stock. are producedby blending these neutrals with the bright stock in the desiredproportion to produce oil of desired viscosity.

' The present invention is related to a process for producinglubricating oils from oils containing asphalt and/or wax. In ourprocess, crude oil containing asphalt and/or wax is topped to remove thelighter fractions of the oil. The topped crude is subsequently treatedfor removal of the asphalt. and/or'wax. We prefer to effect theseparation of the asphalt from the oil by means of solvents'which arecapable of dissolving the oil and which do not dissolve the asphalt.Such vent liquefied normally gaseous hydrocarbons.

The lubricating pils of varying viscosity 1 We intend to include suchliquefied normally gaseous hydrocarbons as methane, ethane, propane,butane, isobutane and mixtures thereof. These normally gaseoushydrocarbon solvents may be obtained by rectification of casinghead 5gasoline by the so-called stabilizing method now conventional in thenatural gasoline industry. They are the overhead obtained and areliquefied by compression and cooled in the conventional manner and aredrawn into pressure chambers 10 where they are maintained in a liquidstate until used. A typical analysis of such a fraction is 6.72% ethane,72.2% propane, 19.91% iso-butane and 1.17% normal butane. Such afraction may be maintained in a liquid state at a pressure of 15 vent,the solution is maintained at a pressure 20 suiiicient to maintain thepropane in the liquid state at ordinary temperatures of about to F., i.e. at about to lbs. per square inch. The commingling of the oil withpropane at such pressures, results in the precipitation of 25 asphaltwhich is separated from the oil as mate.- rial substantially free of oiland consisting chiefly .of pure bitumen. The remaining oil dissolved inthe liquid propane contains substantially all of the lubricating oilcomponents which are pres- 30 ent in the crude oil and in substantiallythe same form as they existed in the original crude oil and also themajor portion of the wax present in the crude oil.

The wax present in the oil may be separated 35 by chilling the oilpropanemixture to low. temperatures to. precipitate the wax after whichthe chilled mass is cold settled, centrifuged or filtered to remove theprecipitated wax from the propane oil solution. One method -foraccomplishing 0 chilling of the oil to precipitate wax is by reducingthe pressure on the propane oil mixture subsequent to asphalt separationunder high pressure to permit vaporization of propane which lowers thetemperature of the oil and causes the wax present to precipitate fromsolution.

We have discovered that many lubricating ofls obtained by the extractionwith solvents, such as propane from crude oil containing asphalt andwax, are composed of fractions which have 50 a relatively high gravityviscosity constant, 1. e.

a relatively high temperature viscosity susceptibility and fractionswhich have a relatively low gravity viscosity constant, 1. e. arelatively low temperature, viscosity susceptibility and that these oilsmay be separated into oils "which exhibit a low temperature viscositysusceptibility resembling oils produced from asphalt free crudes andoils which exhibit a high temperature viscosity susceptibilitycorresponding to oils produced by distillation of asphaltic crudes.

The gravity viscosity constant has been defined by Hill and Coates inthe Journal of Ind. and Eng. Chem. in Vol. 20, 1928, page 641. Thisconstant represents the paraifinicity or naphthenicity of an oil. A highvalue represents a high degree of naphthenicity while a low valueindicates a relatively greater paraffinioity. Lubricatingoils fromnatural crudes range from .903

Eastern Pennsylvaniatype or even beyond. For

. convenience, we will call the oils which exhibit a low temperatureviscosity susceptibility or gravity viscosity constant as paramnoid oroils of high parafiinicity and those which exhibit a high temperatureviscosity susceptibility or gra ity viscosity constant and whichresemble Westem lubricating oil distillates as non-paraffinoidor oils oflow paramnicity. The propane extract which consists of such a mixture ofparafinoid and non-parafiinoid fractions may be separated into theserespective fractions by the use of solvents which will selectivelydissolve out the nonparaflinoid components. We have found that certainsolvents have a selective solvent action for the non-parafunoid oils. Assolvents which will efiect this separation, we have found as usefulliquid sulphur dioxide, mixtures of acetone and benzol, aniline, methylformate, dichlorethyl ether, nitrobenzol, chloraniline, phenol andcresol. Liquid sulphur dioxide, dichlorethyl ether and nitrobenzol havebeen found especially valuable as solvents to separate the propaneextract into oils which exhibit low temperature viscositysusceptibilities and into oils which exhibit high temperature viscositysusceptibilities.

5 of the asphalt and wax with liquid sulphur di- Gill .non-paramnoidcomponents.

oxide in the presence of the liquid propane used to precipitate andseparate the asphalt from the oil. The propane solution of oil isextracted with liquid sulphur dioxide to remove therefrom the Liquidpropane is a good solvent for the paraiiinic fractions but a poorsolvent for the impurities such as the gums, resins and other compoundswhich exhibit high carbon forming characteristics. Furthermore,

. if an oil ,is extracted under the same conditions of temperature andamounts of selective solvent, i. e. liquid sulphur dioxide, with andwithout the use of liquid propane, a greater yield of paraffinoiol oilis obtained when the extraction is carried out in the presence of theliquid propane.

The presence of the liquid propane during, the extraction appears tolower the solvent power of the extractive solvent, the result being thatparafifinic fractions which are normally dissolved in the extract phaseduring the extraction withture viscosity susceptibility of the oil wemay aooaoeo treat it with sulphuric acid. Such treatment removes fromthe oil a portion of the bodies present which possessa high temperatureviscosity susceptibility. The treatment with sulphuric acid ispreferably followed by treatment with clay to remove entrained sulphuricacid sludge which does not separate by settling, and-also to removecoloring matter which imparts a poor color to the oil. It is preferableto effect the chemical treatment with sulphuric acid and clay when theoil is dissolved in the liquid propane for the reason that. the sludgeformed in acid treating the paraifinic fraction or rafilnate produced byextraction with liquid sulphur dioxide is a liquid sludge as contrastedto the hard sludge often obtained on treating lubricating stocksdirectly, that is, without the presence of liquid propane. The softsludge obtained in acid treating the rafilnate becomes emulsified and isdiihcult to make agglomerate and settle from the oil when the treatmentis carried out in the absence of -a very low viscosity diluent such asliquid propane. We have found that by performing the acid treating stepin the process prior to extraction with liquid sulphur dioxide that moreeffective results are obtained. If the oil is not acid treated beforeextraction with the selective solvent, there are present in thelubricating oil stock,

particularly residual oils, certain asphaltic andcolor bodies such asresins and gums which were stage so that a separation of these twophases is very difiicult. in addition, the sulphuric acid ex-- erts aselective action on the most asphaltic and unsaturated bodies of highmolecular weight which tend to give high carbon residues in the-'finished oil.

These bodies are very dimcult to remove with certain selective solventssuch as liquid sulphur dioxide on account of their high molecular weightwhich corresponds to a low solubility in the solvent. removal of thesebodies with a solvent such as liquid sulphur dioxide, aniline ordichlorethylether requires the employment of very drastic conditions ofextraction, as, for example, an excessive amount of solvent or hightemperature of extraction with the result that a portion of the lowmolecular weight high grade material or oil is lost in the extract phasealong with the high molecular weight material. Obviously, the

removal of these most dimcult high molecular weight bodies by acidtreatment prior to exnecessity of employing the above drastic conditionsof extraction which result in a concomitant loss of a portion of thehigh grade low molecular weight oils.

It is preferable to perform the wax separation step prior to extractionof the oil with the selective solvent into fractions of highparaiilnicity and fractions of low parafiinicity for the reason that thelow temperatures of extraction necessary with certain selective solventssuch as liquid sulphur dioxide, cresol and ohloraniline causes the waxto precipitate from solution and this hinders extraction with theselective solvent. For example, the extraction with liquid sulphurdioxide, and choraniline is preferably at 20 to 50 iii. and with cresolat 5 to 20 F. depending upon the type of oil treated. For Californiaoils, the preferred treating temperatures are lower than those forMid-Continent oils. When treating at temperatures belowapproximateh 35 FIn other words, the

wax, if present, will invariably precipitate from solution and hinderthe extraction process. Moreover, it is easier to raise the temperaturefrom a dewaxing temperature to the higher extraction temperature bysimple heating than it is to lower the temperature from an extractiontemperature to a dewaxing temperature.

With the above discussion in mind, it will be perceived that it is anobject of our invention to isolate from crude oil or topped crude oilthose fractions having characteristics which impart to the oil the lowtemperature viscosity susceptibility typical of parafiln base oil.

More particularly, it is an object of our invention to isolate fromasphalt containing oils those components which impart to the oil thereduced susceptibility to change in viscosity with temperature which ischaracteristic of oils obtained from non-asphalt containing oils, thatis, to separate the parafllnoid from non-paraflinoid components of theasphalt containing crude oils.-

It is a further object of our invention to separate asphalt from an oilcontaining asphalt, oil and wax by means of a solvent, to separate thewax from the oil and solvent and subsequently to separate the asphaltand wax free oil by means of a second solvent used in the presence ofthe first solvent into a paraflinoid oil and a nonparafllnoid oil. It isa further object to treat the oil dissolved in the first solvent withsulphuric acid prior to extraction with a selective solvent.

It is a further object of our invention to employ a normally gaseoushydrocarbon solvent, in

, particular liquid propane, as the solvent for separating the asphaltfrom the oil and the use of liquid sulphur dioxide as the solvent forseparating the oil into paraflinic and non-paraflinic fractions.

It is a particular object of our invention to separate the oil,subsequent to the removal of asphalt and/or wax from the oil andsubsequent to chemical purification with sulphuric acid and clay, intoparaflinic and non-paraflinic fractions by means of liquid sulphurdioxide employed in the presence of liquid propane.

Other objects and apparatus of our invention will be apparent from thefollowing description of the invention taken from the drawing whichrefers to a schematic arrangement of apparatus for carrying out theinvention.

Referring to the drawing, an asphalt and wax containing oil, such astopped residuum from which the lighter fractions such as gasoline,kerosene and gas oil have been removed, is taken from tank I and isdrawn into line 2 controlled by valve 3 by pump 4 where it meets astream of liquefied normally gaseous hydrocarbon solvent such asliquidpropane taken from storage tank 5 via line 3 controlled by valve Iand pump 3, which forces the liquid propane via line 9 into line 2. Theamount of propane introduced into line 2 will depend upon the characterof the oil and the temperatures desired inthe wax precipitating decanteror chilling column 43. The mixture of liquid propane and oil containingasphalt and wax is passed through turbulence or mixing coil I3 intoasphalt preclpitator or decanter II where the asphalt present in the oilis precipitated and settles rapidly to the bottom of the decanter as aslurry of substantially pure bitumen or hard asphalt containing some oiland propane. A pressure of approximately 125 to 175 lbs. per squareinch, and a temperature of about 70 to 80 F. is maintained in decanterII. The pressure in decanter II is maintained by means of equilibriumline I2, controlled by valve I4. which is connected to propane storagetank 5.

The amount of propane introduced into the oil will also depend uponwhether it is desired to remove the asphait at the bottom of thedecanter Has a slurry of asphalt and propane, i. e. as a mixture ofsubstantially pure bitumen or hard asphalt and propane, or as a liquidfraction of asphalt containing propane and some oil. If it is desired toseparate the asphalt indecanter II as a liquid fraction, the volumetricratio of propane to oil in decanter I I will be within the range of 0.6to 6.1, depending upon the character of the oil and the degree to whichit was topped. Higher volumetric ratios will precipitate and settle theasphalt as a slurry of substantially pure bitumen and propane containingvery little oil.

The asphalt precipitated in decanter I I is withdrawn via line I5controlled by valve I6 and is forced by pump I! under pressure throughline I8 and heating coil I9 where it is heated to a sufllciently hightemperature to melt the asphalt and vaporize residual propane. Theheated mix-. ture is then passed through line 20 and flashed throughpressure reduction valve 2| into evaporator 22 which operates at a lowerpressure. Superheated steam is introduced into the evaporator throughperforated pipe 23 to supply additional heat and to reduce the asphaltto proper-specification, generally only as regards flash and tirepoints. The overhead from evaporator 22 passing through mist extractor24 is sent through line 25 to cooler 26 and then via line 21 intoseparator 28. The uncondensed propane from separator 28 is sent throughline 29 controlled by valve 33 to the suction of compressor 3I where itspressure is raised to that in the high pressure system, and is then sentvia line 32 to cooler 33 where it liquefles and runs down into propanestorage tank 5 via line 34. Any condensed light oil in separator 28 iswithdrawn via line 35 controlled by valve 36 and condensed water throughline 31 controlled by valve 33. The asphalt is taken from the bottom ofevaporator 22 via line 39 controlled by valve 39' and passed intostorage tank 40.

The overflow from decanter II consisting of propane and oil free fromasphalt but containing wax is sent through line H and pressure reductionvalve 42 into the wax precipitating decanter or chilling column 43. Inchiller" '43 sufficient propane vaporizes to reduce the temperature ofthe remaining oil and propane to asufliciently low temperature whichcauses wax to precipitate from solution. It is preferable to graduallylower the temperature in the chiller 43 at a rate not in excess of 4 F.per minute, which is accomplished by controlling the pressure in thechiller 43 by the proper operation of valve 45 on line 44 and compressor3|. The pressure will be gradually lower in chiller 43 to about 0 to 25lbs. gauge, which corresponds to a temperature of approximately to 0 F.If desired the temperature may be lowered rapidly, as for example at arate of approximately 10 F. per minute until the temperature ofapproximately 35? to 45 F. is reached, after which the temperature maybe lowered gradually to approximately 40,F. to 0 F., at a rate of about3 F. per minute. If suflicient propane is not present in the oil passinginto the chiller 43 to obtain the desired low temperature for waxprecipitation, additional propane may be introduced into" the oilpassing into chilling column 43 to provide for the desired lowtemperature upon subsequent vaporization of propane. The propaneevaporated in the chiller M will pass out of the top through line M,controlled by valve 45 to the suction of compressor 30 where the vaporsare compressed, which are then cooled in cooler 33 and run down intopropane storage tank 5.

Due to the fact that sumcient time must be given to gradually chill thesolution of oil, wax and propane passing into the chiller :33, and tomake the process continuous, a plurality of chilling columns may beprovided which may be operated alternately. However, whenoperating abatch process, merely one of such chilling columnswill be sufiicient.Thus, the entire charge from decanter it may be transferred to thecolumn A13 and the chilling may be accomplished by controlling theoperation of valve 65 on line 66.

The solution of propane and oil containing the wax precipitated byinternal refrigeration, is withdrawn from lines 413 via line 66,controlled by valve ll] and pumped by pump (38 into the vaportight waxseparator or settler 69, where suficient time is provided for allowingthe precipitated wax to settle from solution to the bottom of thesettler. In batch operation, only one of these set-= tiers will suffice,but to make the process continuous, a plurality of such settlers may beprovided which may be operated alternately in order to provide forsufficient settling periods. In order to prevent ebullition in the waxseparator during the wax settling period, pressure is imposed upon thesolution of oil. Tin's is accomplished by maintaining pressure withinthe separator by pump Gil. As the chilled mass in the wax separatorremains in a non-ebullient state the wax settles out and is collected byvanes 5E9 operated by pulley 50 connected to a suitable source of power,not shown. If suficient propane is not present in the wax settler 69 togive good settling of the precipitated wax, additional propane may beintroduced into the wax settler from the propane storage tank 5.Generally. a volumetric ratio of substantially not less than fourvolumes of propane to one of oil should be maintained during the waxsettling operation. The precipitated wax settling at the bottom of thewax separator d9 as a slurry of wax and propane is removed via line 52,controlled by valve 53 and pumped by pump 54! through heater 55 andthrough line 56 into separator 51!. Vaporized propane is passed to thepropane storage tank 5 via line 58 controlled by valve bit, cooler 59,lines tit and 29, compressor 80, cooler 33, and line 34. Thepropane-free wax is withdrawn from the separator 5?, through line iiiand pumped by pump 62 into line 831 controlled by valve 64 into storagetank 65.

The solution of oil and liquid propane and free from asphalt and wax iswithdrawn from the wax settler 49 via line 66 controlled by valve 6? andpumped by pump 68 into line 69, where it meets a. stream of sulfuricacid or other acids coming from storage tank I via line H controlled byvalve 12 and pump 13; The mixture of acid, oil and propane passes fromline 69 through mixing or agitating coil 14 where the mixture isthoroughly agitated, after which it passes through line I into theseparator 16, where the sulfuric acid sludge is allowed to settle out.If sufficient propane is not present in the oil to permit good settlingof the acid sludge, further quantities may be introduced into the oileither into line 69 proper to the sulphuric acid treatment, or it maybe'added into line subsequent to the agitation with sulphuric acid. Theacid sludge settling to aooaooo the bottom of the separator Thiswithdrawn via line ill controlled by valve lift and pumped by pump it)through line 8t through heater til where together with the vapors fromseparator 57,

through cooler'bt, compressor 3i, cooler 33 and propane storage tank 5.

The acid treated oil in separator it dissolved in propane, is withdrawnvia line 89 and passed into clay tower 9b where the oil and propane istreated with fuller's earth, Death Valley clay, diatomaceous earth,bentonite, charcoal and the like, for the purpose of removing anyremaining sludge and neutralizing the oil. If desired, the clay treatingstep may be omitted in order to leave the oil slightly acid. This willfacilitate the subsequent extraction step with liquid sulphur dioxide.

The acid and clay treated solution of oil in liquid propane and freefrom asphalt and wax, is withdrawn from the clay tower Elli via line 90controlled by valve 92 and pumped by pump 93 through heater 5% where itstemperature is raised to an extraction temperature with liquid sulphurdioxide of approximately to 50 F. and even higher. The propane solutionof oil is then passed via line 95 into the lower zone of extractioncolumn 96. The liquid sulphur dioxide from tank 971 is withdrawn vialine 838 controlled by valve 99 and pumped by pump WED through line Hillinto the upper zone oi-extraction column .99. Due to the difference inspecific gravity of the oil introduced into the lower zorhe of theextraction column and the liquid sulphur dioxide introduced into theupper zone of the extraction column these two liquids tend to separate.7 As the liquid sulphur dioxide descends through the extraction columnit dissolves certain components present in the oil comprising thefractions in the oil of low parafiinicity, leaving undissolved thefraction of high parafilnicity dissolved in the liquid propane. It ispreferable to effect the extraction with liquid sulphur dioxide in thepresence of two volumes of propane to one volume of oil.Approximatelytwo to three volumes of liquid sulphur dioxide should beemployed to obtain the desired separation of the oil into Daraffinic andnon-parafiinic fractions.

The solution of' liquid sulphur dioxideand oil is removed from theextraction column 96 via line are, controlled by valve m3 and sent bymeans of line MM into vaporizer not, where the sulphur dioxide presentin the oil is vaporized by aid of steam circulated through closed coilHi6 and passes through line Hill, controlled by valve W8, compressor )9and then'to condenser E it where the sulphur dioxide is liquefied andsent via line ill into separator M2. The sulphur dioxide solubleconstituents of the oil or extract are removed from the bottom of thevaporizer Hi5 via line Ht, controlled by valve H5 and sent to storagetank H6.

The ascending column of oil in extraction column 96 dissolved in liquidpropane and from which "the liquid sulphur dioxide soluble componentshave been removed passes via line H controlled by valve H 8 into anauxiliary separator H9 where any remaining liquid sulphur dioxidepresent in the oil and components soluble in liquid sulphur dioxide,which were not settied in extraction column 96 are settled out andpassed via line I 26 controlled by valve I2I into line I to thevaporizer I115. The fraction of oil in auxiliary separator II9 passesvia line I 22 into evaporator I23 where the propane and sulphur dioxidepresent in the oil are vaporized by the aid of steam circulated throughclosed coil I24 and are sent via line 125 controlled by valve I26 tocompressor I69, condenser III) via line III into separator II2 where thepropane is separated from the liquid sulphur dioxide and passes via lineI21 controlled by valve I26 and pumped by pump I29 via line I30 topropane storage tank 5. The liquid sulphur dioxide in separator H2 iswithdrawn via line I3I controlled by valve I32 and pumped by pump I33 toliquid sulphur dioxide storage tank 91. The treated oil in evaporatorI23 which has been freed from propane and sulphur dioxide is removed vialine I34 controlled by valve I35 and passed to refined oil tank I36.

The foregoing example is merely illustrative of a preferred method ofcarrying out our invention and is not to be taken as limiting, as manyvariaations may be made within the scope of the following claims byanyone skilled in the art.

We claim:

l. A process for the treatment of mineral lubricating oil whichcomprises dissolving said oil in a liquefied normally gaseoushydrocarbon solvent, treating the diluted oil with sulphuric acid,extracting the acid treated and diluted oil with a selective solvent fornon-paraifinoid fractions to form a fraction dissolved in said diluentand a fraction dissolved in said selective solvent and separating saidfractions.

2. A process according to claim 1 in which the liquefied normallygaseous hydrocarbon is liquid propane and the selective solvent isliquid sulphur dioxide.

3. A process according to claim 1 in which the liquefied normallygaseous hydrocarbon is liquid propane.

4. A process according to claim 1 in which the acid treated oildissolved in the hydrocarbon diluent is treated with clay.

5. A process for the treatment of an oil containing "asphalt whichcomprises commingling said oil with an asphalt precipitating solvent toprecipitate asphalt, separating the asphalt from the oil dissolved insaid solvent, treatingthe oilsolvent solution with sulphuric acid,extracting the acid treated oil dissolved in the asphalt precipitatingsolvent with a selective solvent for nonparaiiinoid fractions to .i'orma fraction dissolved in the asphalt precipitating solvent and a fractiondissolved in the selective solvent and separating said fractions.

6. A process as claimed in claim 5 in which the asphalt precipitatingsolvent is a liquefied nor-' mally gaseous hydrocarbon.

7. A process as claimed in claim 5 in which the asphalt precipitatingsolvent is liquid propane and the selective solvent is liquid sulphurdioxide.

' 8. A process for the treatment of hydrocarbon oil containing wax whichcomprises dissolving said oil in a liquefied normally gaseoushydrocarbon diluent, chilling the diluted oil to precipitate wax,separating the precipitated wax from the diluted oil, treating thedewaxed and diluted oil with sulphuric acid, extracting the dewaxed andacid treated diluted oil with a selective solvent for non-paraflinoidfractions to form an oil tracchilling is produced by vaporizing aportion of the diluent from the oil solvent solution.

a 10. A process according to claim 8 in which the selective solvent isliquid sulphur dioxide.

11. A process for the treatment of oil containing asphalt and wax whichcomprises commingling said oil with an asphalt precipitating solvent toprecipitate asphalt, separating the asphalt from the oil and waxdissolved in said solvent, chilling the waxy oil dissolved in saidsolvent to precipitate wax, separating the precipitated wax from the oildissolved in said solvent, treating the oil dissolvedin said solventwith acid, extracting the acid treated oil dissolved in the solvent witha selective solvent for non-paraflinoid fractions to form a fractiondissolved in said asphalt precipitating solvent and a fraction dissolvedin said selective solvent and separating said fractions.

12. A process according to claim 11 in which the asphalt precipitatingsolvent is a liquefied normally gaseous hydrocarbon.

13. A process for the treatment of crude oil which comprises dissolvingsaid oil in a liquefied normally gaseous hydrocarbon solvent,treatselective solvent and separating said fractions.

Unruc B. BRAY. CLAUDE E. swm'r.

separating said

